Process and apparatus for recovery of mercury from ores containing it

ABSTRACT

A process and apparatus for the recovery of mercury from mercury ores comprises heating a body of the ore in a closed chamber to decompose it into mercury and other vapors, transferring the vapors by means of a jet of injected air to a condensing system formed by at least one generally spirally disposed horizontal conduit having its lower portion open and immersed in a body of cooling water and its upper surface cooled by a water spray, and collecting the condensed liquid mercury in a trough containing the water located under the conduit, and having a sloping bottom to facilitate collection.

United States Patent [72] Inventor [54] PROCESS AND APPARATUS FORRECOVERY OF MERCURY FROM ORES CONTAINING IT 8 Claims, 5 Drawing Figs.

[52] 1.1.8. Cl 75/81, 266/16 [51] Int. Cl C22b 43/00 [50] Field ofSearch 75/81, 1,6; 266/16 20, 24, 9

[56] References Cited UNlTED STATES PATENTS 1,728,359 9/1929 Ormont75/81 2,302,841 11/1942 Connolly 75/81 Primary Examiner-Winston A.Douglas Assistant Examiner-A. Skapars Attorney-Imirie & Smiley ABSTRACT:A process and apparatus for the recovery of mercury from mercury orescomprises heating a body of the ore in a closed chamber to decompose itinto mercury and other vapors, transferring the vapors by means of a jetof injected air to a condensing system formed by at least one generallyspirally disposed horizontal conduit having its lower portion open andimmersed in a body of cooling water and its upper surface cooled by awater spray, and collecting the condensed liquid mercury in a troughcontaining the water located under the conduit, and having a slopingbottom to facilitate collection.

. PATENIEDncI 2s I97l SHEET 10F 4 IMVENTOR Ruiz MONTES De 05,4

LEOPOLDO PATENTEDum 26 191i SHEET 2 BF 4 [.IIIHHHHHHH n m mm WW I M H IMH H mm PATENTEUUC-T 26 ml SHEET 30F 4 INVENTOR LEOPOLDD um MoMTEs De06A IMVEMTR LEOPMDG MONTES De MA PROCESS AND APPARATUS FOR RECOVERY OFMERCURY FROM ORES CONTATNTNG llT SUMMARY OF THE INVENTION The presentinvention provides a new process for beneficiation of mercury from orescontaining it, which fundamentally consists of achieving a sublimationof these ores to obtain mercury vapors, rapidly and with greatcleanness, to afterwards condensing the obtained vapors using novelaspects, that result in the attainment of a greater amount of mercury,carried out readily, economically and with a high degree of cleanness.

The first step in the process, i.e., the sublimation of the ores toproduce mercury vapors is carried out in an industrial furnacecharacterized by having an isolated recess or hermetically sealedchamber, related to the fireplace or heat source, inside of whichthecalcination of the ores is carried out, thus preventing the sublimationproduct vapors from mixing with gases and waste gases evolving from thecombustion of the furnace heat source; said recess having duly connectedat the top thereof an air injector needed for handling the productvapors from sublimation. This industrial furnace has a heat source andfireplace wherein the temperature is raised to the desired rate and astack to allow for the outflow of the combustion gases and waste gases,which are completely independent from the ores calcination chamber;i.e., the furnace is unique in that the calcination recess or chamberreceives heat only from the furnace fireplace, without intermixing withthe gases and waste gases from the necessary combustion to raise thetemperature.

The ore to be treated is placed in trays or containers of a suitablesize to be introduced within the hermetically sealed and isolated recessin the furnace. The duly crushed ore is placed in said trays extendedover the entire surface thereof without forming a thick layer, toobtain, by placing the material in this way, a larger calcination oresurface and readily attain the entire sublimation of ore undertreatment.

The calcination recess or chamber is fed by introducing the trayscontaining the ore and removing them after calcination has beenachieved, which simplifies and facilitates the tedious task of feedingand discharging the furnace.

When the trays containing the crushed ores are placed within thecalcination chamber and after starting the furnace operation, the orereceives heat transmitted through the hermetically sealed walls of thecombustion recess or chamber, without the ore having direct contact withthe combustion process. When the temperature within the chamber israised to a sufficient level, the ore starts to sublimate, evolving atfirst water vapor, then sulfur vapors and finally mercury vapors.

As the vapors evolve, following the physical laws of the gases, theyhave a tendency to move upward and are received in the upper part of thechamber, which chamber constitutes a gasification chamber. As the vaporsremain in said gasification chamber they can be handled at will byintroducing air into the chamber through an air injector speciallyconnected for this purpose. When the air is introduced within thegasification chamber a continuous steam of vapors is formed, which aredrawn by the draft pipe to be carried through a duct into the condensersarea for further treatment.

By means of this process used for the sublimation of the ore, thecontamination of the vapors obtained, which are later treated in thecondensers, with the exhaust gases and debris resulting from combustionof the heat source in the furnace, is prevented, the system therebyproviding for the attainment of great purity in the vapors to betreated, and furthermore, a voluntary handling of the vapors means ofair injection can be achieved.

The high-purity vapors obtained by the sublimation process abovementioned, are carried through an hermetically sealed duct into thecondensation system wherein they are to be treated.

This new condensation system for the mercury vapors treatment comprisesa high-capacity container containing water at a permanent level; overthis permanent water surface there is a hollow half-round or invertedtubular half-section which extends horizontally with the bottom portionof its opposite walls immersed into the permanent water level, thusforming a closed duct, the web of which is formed by the sidewalls andthe roof of the tubular half-section or half-round and at the bottomthereof by the surface levell of the water or water bed. The duct thusformed has its bottom part or floor constituted by the permanent waterlevel in its complete cross and longitudinal extension, i.e., thecontinuous bed or floor formed by the permanent water level is acontinuous seal that prevents the leak of the vapors to be treated fromthe duct.

The mercury vapors obtained by the ore sublimation within thehermetically sealed recess or chamber in the furnace, can be controlledat will by the air injector to be selectively exhausted through theclosed duct to be carried to the condenser itself, in which the coolingprocess starts, using as refrigeration means the continuous seal ofwater of the condenser duct and the water sprinkled over the sidewallsand the roof of said duct by a sprinkler system.

While the vapors remain and slowly move inside the cooling duct, theycondense slowly by cooling upon contact with the cool walls of the ductand with the water forming the duct bed. As the cooling process of themercury vapors accelerates, these are condensed and deposited on theseal or bed of water, already in the liquid form presented by this metalin its natural state, and mercury precipitates, by gravity, to thebottom of the water container. This treatment is carried on untilwaterimmiscible, complete condensation of the mercury vapors isattained, whereby the extension of the duct with the continuous waterseal will be dependent on the amount and temperature of the vapors to betreated, the residues of which, after treatment, are exhausted from thecondenser by means of a stack located at the end of the continuous watersealed duct, which vapor residues are so poor in metal contents that afurther condensation is not possible, as they are thrown out at atemperature of 20 C. or less.

Mercury, already in its natural state, deposited on the water surfacesealing the bottom of the duct, falls by gravity to the bottom of thecontainer, and this step can be accelerated by moving or stirring thewater. Mercury settles on the bottomof the water container, and thisbottom provided with a slant allows the slipping of the mercury which isconcentrated at a given single spot from where the metal can berecovered through a siphon trap. Since mercury in its natural state iswater-immiscible, during the precipitation through the water and slidingthereof on the bottom of the container, it leaves its contaminatingimpurities as debris suspended in the water of the container, thus beingrecovered in a simple manner and with a high degree of purity.

BACKGROUND OF THE INVENTION 1. Field of the invention The presentinvention comprises a new process for the beneficiation of the mercuryfrom ores containing it, pertaining to the field of ore beneficiationand, in particular, to beneficiation of mercury-bearing ores, such ascinnabar, calomel, coccinite, argental mercury, tremanite, etc., sinceit allows, by the treatment of these ores, the attainment of a perfectsublimation of the same, maintaining the vapors to be treated at ahigh-purity level, to further advantageously condense them by the novelsystem of a continuous water seal or bed in the condenser ducts.

This invention satisfies a very important need within the miningindustry devoted to the beneficiation of mercury, as through the usethereof the calcination process expedited a better sublimation of theores is attained, the vapors to be condensed are kept with a higherdegree of purity, the condensation process is accelerated, the generalmaintenance of the equipment is made easier, the exit of toxic gasesharmful to the workers is avoided and, above all, a greater amount ofmercury is obtained as compared with the industrial processes presentlyin use, which allows working with very low-grade ores whosebeneficiation through other processes is not economical. The fact thatwhen using the present process up to a 95 percent of the mercurycontained in the ores is obtained, is of great importance, thus avoidingthe unnecessary waste of this rare ore which constitutes one of the mainnonrecoverable natural resources of Mexico.

2. Disclosure of the up-to-date knowledge in the field of the presentinvention:

Mercury was known since ancient times and at the beginning it wasobtained in rare natural deposits where it was found in its naturalliquid state.

The first known method for obtaining mercury is the one described byTheophrastus in the year of 321 B.C. in his Treaty on Stones, wherein hepoints out that it is possible to obtain mercury by crushing naturalcinnabar with vinegar in a copper mortar.

Argentium vivum or hydrargyrum, as it was known in an cient times, couldalso be obtained by heating natural cinnabar in an iron vessel and thenallowing for the cooling of its contents, according to a methoddescribed by Dioscorides in the first century of our era. Later on, inthe eighth century of the Christian Era, Geber asserted that mercurycould be obtained by distillation over lime, glass or salt. The Arabs,to obtain the "azogue (quicksilver), as they named it, used a processknown as Xabecas, by which clay kettles were restrained within thefurnace where the cinnabar was calcinated. It was not until 1693 that inthe Peruvian mines of Huanacavelica an effective method was developed,which process comprises the calcination of the ore and the furthercondensation of vapors thus obtained in buckets; the inventor of thisprocess was Lope Saavedra y Barba.

The main processes used at present to obtain mercury in an industrialform are the following:

Retort furnaces process: These furnaces are tubes where the I ore isintroduced by shoveling, the opened ends of the tubes are then closedand the ore is calcinated; the vapors of which are exhausted through astack together with the exhaust gas and combustion debris. When thematerial has been calcinated the slag is removed from the tubes by hand,whereby the workers are exposed to the toxic vapors evolving from thehot residues. The condensation chamber in this process is built withfirebrick and cement lined in the inside, thus causing very oftencrackings in the floor and in the walls through which vapor escapecausing high losses, This process provides a yield of mercury from theores of at most about 60 percent it should be noted that this is theprocess used mainly at present in Mexican mines.

Espirett Furnace: This is a rectangular furnace where alternate layersof charcoal and the ore to be treated are arranged, then combustion isstarted in the charcoal layers to achieve calcination; its condensingsystem comprises closed cement-lined ducts made out of bricks. Thissystem is also widely used in our mines for beneficiation of mercury andwas introduced in Mexico during the last century.

GouldFurnace: This is a horizontal tube lined in its inner wall withrefractory bricks and mounted with a slight slope, having a rotationalmovement and a continuous feed and discharge of ores. Calcination iscarried out with direct fire on the tube outside wall; then the vaporsobtained together with the fuel gases and combustion debris dischargeinto the condensation system formed by metallic pipes arranged withzigzag sections having at the bottom vortex thereof small water pocketswhere liquid mercury is deposited.

Herreshoff Furnace: This system is formed by a cylindrical verticalfurnace of sheet metal structure lined on the inside walls withrefractory bricks, sometimes 50-feet high; in the inner portion of thefurnace there are recesses where the ore is placed by means of arotatory central column which conveys the ore from one recess to theanother until calcination is completed. The condensing system isgenerally the same as in the Gould Furnace.

Scott Furnace: This is a vertical type furnace with a continuous chargeand discharge system and a condensing system similar to the ones in theGould and Herreshoff furnaces.

The above systems are the ones more often used by the mining industryspecialized in mercury beneficiation, and therefore it is pertinent topoint out the advantages that the new, above-described, process have ascompared with all of the systems presently used; which can be summarizedas follows:

a. A rapid feed of the ores to be calcinated inside the hermeticallysealed chamber, as this step is carried out in trays preloaded withcrushed ore, thus avoiding the health harmful dust evolving from the orethat might clog the ducts in the system; as well as, due to theswiftness and ease of the operation, costly heat waste in the furnace isavoided.

b. This system has a calcination and evaporation hermetically sealedchamber to effect therein the sublimation of the ore to be treated,thus, as the chamber is hermetically sealed, preventing contamination ofthe mercury vapors with combustion debris, formed by undesired gases,ashes and dust, which might enter into the condenser clogging the ducts,and greatly increasing the equipment maintenance work, and above all,hindering the effectiveness of the condensation process, which resultsin great losses of mercury vapors.

c. Due to the distribution of the ore batch to be treated in the trays,which distribution consists in providing the ore with a great surfaceore and reduced thickness, the furnace temperature can be transferred inoptimum form over the entire surface of the ore, thus achieving anhomogeneous calcination and therefore, fuel savings.

d. Due to the unique distribution of the ore to be calcinated a largerburning surface is achieved, therefore obtaining a more efl'ective oresublimation.

e. When sublimation of the ore takes place within the hermeticallysealed chamber, depending on the different sublimation temperatures,water vapor is first evolved, then sulfur vapors and finally mercuryvapors, which gases can be controlled at will by means of theair-injecting system to the hermetically sealed calcination chamber, andthe water and sulfur vapor can be readily removed, leaving only highdegree of purity mercury vapors which are further treated afterwards.This vapor control by means of injected air is quite important as itallows the quick removal of undesired vapors that might hinder thecondensation process of the mercury vapors, and at the same time, thisvoluntary and controlled air injection completely prevents thestationing and combination of the various gases evolving from thesublimation of the ore which represent a big problem in thebeneficiation of mercury process, as it promotes reversion of thephysical-chemical process in which the different gases are molecularlyrecombined resulting in synthetic untreatable mineral which represent ahigh loss in this field of the mining industry.

f. By operating the novel mercury condensation system, comprising ahorizontal cooling duct sprinkled cooled, and with a continuous waterbed or seal, there is achieved a fast and effective condensation ofmercury vapors thus recovering mercury in its natural state as containedin the vapors up to a yield of percent.

g. By means of the air injection into the calcination chamber avoluntary control of the gases to be treated is achieved, and the pathof mercury gases through the condenser can be slowed down oraccelerated, as needed, to achieve optimum condensation of said gases.

h. Mercury condensed within the cooling duct is deposited over theadjacent water bed or seal, and then, by gravity, drops into bottom ofthe water container whose bottom has a slant over which the mercuryslides until it concentrates in a single spot, from which through asiphon trap mercury is recovered cleanly, readily and in a high-puritystate.

i. Once the sublimation and condensation of a given amount of ore iscompleted the trays containing calcinated ores are quickly and readilywithdrawn from the hermetically sealed calcination chamber, and arereplaced by another batch of loaded trays, thereby saving time, avoidingheat loss from the furnace and protecting the workers from extendedcontact with the highly toxic mercury vapors.

j. In this system of obtaining mercury, when vapors to be condensed areseparated from the combustion debris and gases, the clogging of theducts by said debris is prevented, thus avoiding the need for thetiresome task of cleaning the ducts periodically thus reducing the highcost involved in the maintenance of the equipment, and besides ahazardous job for the workers in charge of this operation is alsoavoided. Through the novel system of charging and discharging ores toand from'the hermetically sealed recess of the furnace by means oftrays, there is also avoided the extended contact of the workers withthe highly toxic mercury vapors which cause a high degree of mortalitybetween those workers devoted to this task. This is one of the mainadvantages offered by the present system of beneficiating mercury, as itavoids the drawbacks of mercurialism either in its acute form,represented as stomatitis gastralgia or dysentery or in its chronic formas intoxication through skin and the respiratory tract.

k. This process for obtaining mercury also allows for the beneficiationof very low grade minerals which are presently considered aseconomically untreatable,'since by means of the use of this process itis possible to attain up to 95 percent of mercury borne by differentores containing the same. There is also of great importance the factthat, by using this process, it is possible to attain up to 40 percentmore mercury, as compared to the methods employed in the present daysrepresenting a great economical benefit as well as great savings in themining reserves of this important nonrecoverable natural resource.

BRIEF DISCLOSURE OF DRAWINGS:

FIG. I is a side elevation view of the complete arrangement, wherein thefurnace, duct and condenser are shown with all the parts appearing fromthis angle, duly numbered, as well as the section lines for taking thesubsequent figures.

FIG. 2 is a side elevation view in longitudinal cross section of thearrangement wherein the furnace, duct and condenser are shown with allthe parts appearing from this angle, duly numbered.

FIG. 3 is a plan view of the arrangement, with a cross section of thefurnace following the line 3-3 of FIG. I, wherein the furnace, duct andcondenser are shown with all the parts appearing from this angle, dulynumbered.

FIG. 41 is an elevational view of the furnace and a section taken inline 4-4 of FIG. I, wherein all the parts appearing from this angle areshown, duly numbered.

FIG. 5 is a plant view of the condenser and a section taken on line S-5of FIG. 1, wherein all the parts appearing from this angle are shownduly numbered.

DISCLOSURE OF THE MAIN PARTS OF THE INVENTION The numeral order to beused hereinafter, identified with arabic characters, is the same asobserved inall the five Figures of the drawings, to illustrate alwaysthe same parts. The various elements of the apparatus are designated asfollows:

ill. Furnace and all the elements thereof.

12. Heat source or furnace burner.

13. Combustion chamber or fireplace of furnace.

I4}. Exhaust stack or chimney for combustion gasses and waste from thefurnace.

Isolated and hermetically sealed recess or chamber for calcination andsublimation of ore.

16. Evaporation chamber wherein the vapors produced by the sublimationof ore are deposited, to be carried over into the condenser.

I7. Tight closing door of the calcination chamber or recess.

18. Container or tray wherein the ore is deposited in order to chargeand discharge said calcination recess.

19. Air injector for the voluntary control of the movement of gassesinside the gasification chamber and the condenser.

20. Exhaust draught pipe for vapors from the calcination chamber, to betreated at the condenser.

21. Enclosed duct for transferring the vapors from the calcinationchamber into the condenser.

22. Mercury vapors condenser, and all the parts thereof.

23..Support means for containers or tubs.

24. Containers or tubs containing water and the cooling duct.

25. Water in the tubs at a permanent level.

26. Sloped or slanted bottom of the container or tub on which mercuryslips down in its natural state to be collected in a single spot.

27. Siphon trap for collecting liquid mercury.

28. Tube or intake way for water, to fill up the containers or tubs.

29. Overflow tube from the upper container into the lower container, inorder to maintain a permanent level at the water surface in the uppercontainer.

30. Exhaust or drain tube for water in the lower container to maintainthe permanent level of water at the surface thereof.

31. Discharge or drain hole of the containers or tubs.

32. Cooling horizontal duct with continuous water bed or seal.

33. Draught pipe for carrying the treating vapors into the secondsection of said condenser.

34. Stack for wastes and vapor debris already treated in thecondensation system.

35. Supports for the horizontal duct provided with continu ous water bedor seal.

36. Water sprinkler for cooling down the walls of the duct provided withcontinuous water bed or sea].

DISCLOSURE OF THE PREFERRED EMBODIMENT OF THE INVENTION AND ITSOPERATION Making now a more specific disclosure of the apparatus and theseveral steps of the process of the present invention, their severalparts will be mentioned hereinafter, identifying the same with the samearabic characters, as far as the same be apparent in any of the fiveFigures of the accompanying drawings.

The process for beneficiating mercury from ores containing the same,consists of two basic steps wherein the novel fea tures are presentedreferring the processes now in use. The first step consists in thesublimation of the elements contained in the ores to be treated, in sucha form as to obtain high-purity vapors, using the ore at the maximumyield thereof, making the work in an easy and quick manner and to ahigh-securitylevel regarding the health of the workers. Once the vaporsare obtained, they are controlled at will by means of an air injector inorder to pass them, in due time, into the condensation system, whichsystem is characterized by the novel feature, relative to the prior artsystems used for the condensation of mercury vapors, of passing thevapors through a horizontal cooling duct which is cooled by means of asprinkling system in the outside, which duct has a continuous water bedor seal to accelerate the cooling of the treating vapors and to recovermercury as released from vapors, already in its natural liquid state.

The first step is effected in an apparatus having an industrial furnace11 having a heat source or burner 12 which increases the temperature upto the desired level inside a combustion chamber or fireplace 13; thiscombustion chamber 13 having a stack 14 through which the combustiongasses and debris coming from the combustion chamber or fireplace I3 areexpelled. This furnace is characterized by having an isolated andhermetically sealed recess 15 inside which the calcination andsublimation of ore to be treated is effected, which recess orhermetically sealed chamber is completely isolated regarding thefireplace of said furnace 13, from which only receives heat through thehermetically sealed walls to attain the sublimation of ore locatedinside the said chamber or recess 15, this chamber having a tightclosing door 17 which opens to allow for the pass into the container ortray 18 wherein ore to be subjected to treatment is located. in theupper inner position of said calcination recess 15 there is a spacewherein the gasses from sublimation remain, this space constituting anevaporation chamber 16 into which it is possible to inject air throughan air inductor 19, coupled to said chamber 16.

The ore to be treated is positioned, upon being duly crushed, on thetray or batch container 18 in such a form as to present a spread surfaceand small thickness, said tray 18,

once duly charged, is introduced into the hermetically sealedcalcination chamber 15, and the door 17 of this chamber 15 ishermetically tight-closed. Furnace 11 is then started by firing the heatsource or burner 12 thus increasing the temperature of the combustionchamber or fireplace 13, which temperature is transmitted through thetight walls of the isolated calcination recess 15 in order to obtain thedue sublimation of the ore deposited on the container or tray 18 locatedinside the calcination recess 15; the temperature to which the ore issubjected must be above 400 C., but always below 650 C., in order toavoid the reversion of the physical-chemical process of sublimation.

Gases and wastes produced at the combustion chamber or fireplace 13 dueto the effects of said combustion, are exhausted through a stack whichis completely independent relative to the exhaust or draught hole forthe mercury gasses to be treated.

When the ore deposited'on the tray or container 18 located inside thecalcination recess, receives the constantly increasing temperature, itstarts to sublimate steam when the temperature raises up to 120 C.,sulfur vapors when said temperature reaches to 220 C., and mercuryvapors when said temperature arises up to an average temperature of 400C.; all of these vapors following the Gas Law, move upward and depositon the inner upper part of the calcination recess 15, which constitutesthe evaporation chamber 16, wherein, by means of air injection, thevapors are controlled in order to handle and pass the same into theexhaust draught 20 for .vapors to be treated, which draught communicateswith the enclosed duct 21 through which said vapors are transferred intothe condensation apparatus. This exhaust for the vapors to be treated isabsolutely independent as regards the exhaust stack 14 for gases anddebris from the combustion chamber or fireplace 13, for which reason themercurial vapors are in a high degree of purity in order to be treated,in addition to allowing for the first and second sublimation vapors,i.e., those from water and sulfur, to be discarded quickly when the airinjector 19 is started, so as to form an air current in the inside ofthe evaporation chamber 16 to exhaust the same through the exhaustdraught for the gasses to be treated 20 and discard the same easily soas to avoid a contamination therewith of the mercury vapors produced atmean temperatures of 400 C. The mercury vapors remain at the evaporationchamber 16 and are forced, by means of voluntary air injection, throughthe exhaust draught for the vapors to be treated 20 and into the closedduct 21 across which said vapors are carried and into the condensationapparatus 22 wherein they are to be further treated.

Due to the array of the ore inside the tray or container 18, presentingan extended surface and small thickness, the homogeneous calcination ofore is facilitated, whereby the sublimation of all the metals borne bythe ore is allowed thus obtaining the maximum yield from the ores bymeans of this system of beneficiation by sublimation.

Once the entire calcination of ore inside the isolated and hermeticallysealed calcination recess 15 is completed, the door 17 of said recess 15is opened and the tray 18 is removed containing the calcinated oreresidues, and immediately is replaced by another tray 18 having freshore duly positioned. in order to be subjected to the calcination andsublimation treatment. This system of charging and discharging ore canbe effected in a simple and very easy manner, thus avoiding the heatloss of the furnace 11 which, in turn, means fuel savings; furthermore,this process of charging and discharging avoid the exposure of workersto the continuous emanation of mercuric vapors, as occurs in all of theprocesses presently in use, which implies a great benefit for theworkers during their labor, by avoiding an extended contact with toxicmercuric vapors.

When the tray container 18 containing the calcinated ores debris is withand a new container 18 with ore to be sublimated at the calcinationrecess 15 is introduced, and the door thereof 17 is hermetically closed,a calcination and sublimation cycle is ended and another one isimmediately started, thus being possible to work in a continuous manner,and to avoid the tiresome tasks of discharging the furnace and coolingthe same, as occurs with the processes presently in use.

The second step of the process for beneficiating mercury is carried outin a condenser apparatus for mercury vapors 22, which apparatuscomprises water at a permanent level 25 over which extends a horizontalduct formed by a hollow halfround or reversed half-tubular section, thelower part of the opposite walls of which are immersed under thepermanent water level 25, thus forming an enclosed duct 32, the web ofwhich is formed by the walls and roof of said inverted half tubularsection or hollow half-round, and the floor formed by the continuouswater bed at a permanent level; said duct 32 thus formed having itslower part or floor formed by the permanent water level throughout thecross and longitudinal length, i.e., said bed or continuous floorconstituted by the permanent level water forms a continuous seal forsaid duct 32 avoiding the leak therefrom of the treating vapors. Thishorizontal duct 32 provided with said water bed or seal is provided witha cooling system formed by tubing or sprinklings covering the same witha cool water blanket outside the same, in order to decrease thetemperature of the treating gases, and supported by supports 35 fixingthe same to the upper part of the walls of said tub or container 24.

Said containers or tubs 24 containing water 25 and the coolinghorizontal duct 32 are supported by support means 23 maintaining thesame at the necessary height so as to expedite the condensation process,as needed for each particular case. Said containers or tubs 24 aresupplied with water, both by the sprinkling tubes 36 and by an inlettube 28. Water is introduced into the containers or tubs 24 and theseare filled up to the permanent level of the water surface 25 determinedby the overflow tubes 29 and 30 located at the containers or tubes 24 atthe desired height for the permanent water level These tubs orcontainers 24 have an inclined bottom 26 to expedite the mercurycollection in its liquid state and at the lowermost part of said slopedbottom 26 have a siphon trap to trap therethrough all mercury depositedon the bottom of said container or tub 24. These tubs or containers 24are provided with a drain hole 31 to drain out the water for cleaningand equipment maintenance purposes.

In the mercury vapors condensation apparatus the horizontal cooling ductequipped with continuous water seal 25 is comprised'of more than asingle container or tub 24 is also provided with a treating vaporsdraught pipe 33 to carry said vapors into the subsequent condensationunits; said horizontal duct provided with continuous water seal or,bedending at a stack for the wastes and debris of the already treatedvapors 34.

The mercury vapors exiting from the evaporation chamber 16 are handledby means of an air current, forcing the same to leave said chamber 16through the draught hole for mercury vapors 20 to be carried over bymeans of closed duct 21 into the apparatus wherein the condensation isto be carried out.

When leaving said chamber 16 the vapors carried across the duct 21 areat a temperature ranging between 400 C. and

500 C., and the cooling process thereof starts when said vapors passacross the closed duct 21 to enter the cooling horizontal duct providedwith continuous water bed or seal 32, located at the upper part of thecontainers or tubs 24. Inside this duct, cooled in the outside of thesame by means of sprinkling devices 36, said mercury vapors begin toloss caloric units during their advance in the inside of duct 32thereof, since both the cool walls of this duct 32 and the water of thebed or sea] 25 have a great temperature difference as high compared tosaid vapors, whereby said treating vapors, when contacting the ductwalls 32 and water seal 25, are cooled down thus starting the mercurialvapors condensation itself.

Upon condensation of the mercury vapors they pass the natural liquidstate of mercury, and this latter deposits in the form of small drops onthe water bed or seal 25 of said condensation duct 32, and henceprecipitate by gravity into the slanted bottom 26 of said container ortub 241, sliding down thereon into the lowermost part of said bottom 26,wherein it is concentrated, and hence, passes to the siphon trap throughwhich is recovered.

Said cooling horizontal duct 32 with continuous water seal 25 has apredetermined extension allowing for a decreasing temperature of thetreating vapors to take place, down to 20 C., in order to perfectlycarry out the vapors condensation process to which end the size of thecooling units is determined depending on the volume and temperature ofvapors, so as to be able to cool down the same at a temperature of 20 C.or less.

In this instance, the mercury vapors travel through the duct web 32 andfor each meter of said travel, they decrease their temperature, thusenabling an accelerated condensation process of said gaseous bodies aswell as the conversion into mercury in its natural liquid state whensaid mercury vapors are condensed during the travel across said coolingduct 32 of the first unit; then, they ascend through the treating vaporsdraught pipe 33 to be again subjected to the cooling and condensingprocess at the next unit of said apparatus, wherein the travel is againeffected across the horizontal duct web provided with continuous waterbed or seal 25; and upon ending the travel, the temperature of saidvapors must be lowered at 20 C. or less and, therefore, the wholecondensation of these vapors has been carried out, which vapors arefinally vented through a stack 34 for the waste and debris of themercurial vapors already treated.

As said mercury vapors travel inside said cooling horizontal ductprovided with continuous water seal or bed 25 they are cooled down uponcontacting the duct walls 32 and the permanent water level 25, and thevapors condensation process is thus accelerated, with mercury beingdeposited on the continuous water bed or seal in its liquid naturalstate but when the optimum level has been reached, the condensationprocess decreases, thus being recovered a less amount of mercury due tothe poorer state of the vapors traveling the duct 32.

As mercury in its natural state is immiscible, when it precipitates onthis water body 25 and while falling on the sloped bottom 26 of saidcontainer or tub 2d, said mercury is washed eliminating thecontamination impurities, suspending them in water, which phenomenonenables the final recovering of mercury in a high purity state.

At said cooling duct 32, there are also condensed both water vapors andsulfur products from the sublimation or ore, the former being convertedinto water and the latter being suspended in water 25 of said container24, thus avoiding the clogging of said duct 32 by sulfur, and minimizingthe maintenance of this condensation apparatus, both in costs and inlabor.

This process is carried out in a continuous form by conducting saidmercury vapors across the cooling horizontal duct provided withcontinuous water seal 25, injecting air by means of the air injector 19,specially coupled to the evaporation fected in an uninterrupted manner.

It should be understood that the shape of the apparatus for thebeneficiation of mercury constitutes a feature of this invention that isdescribed and illustrated just as an example thereof, but the basicprinciples of this invention can be varied even by changing thearrangement of some of the mentioned elements, always within the spiritthereof.

The apparatus needed for carry out the new process of beneficiatingmercury from ores containing the same, becomes thus just an example ofthis invention and it is to be understood that anyone in the art towhich pertains this invention, can resort many variations, withoutdeparting from the scope of the invention, as defined in the appendedclaims.

l claim:

1. Process for recovering mercury from mercury ores, comprising thesteps of:

a. heating a body of mercury ore in an enclosed heating zone of afurnace and out of contact with the combustion gases forming the heatsource from said furnace for a period of time sufficient to decomposethe ore into vapors of mercury and other ore constituents;

. collecting said vapors in the upper portion of said heating zone;

c. transferring said vapors out of said heating zone by injection of astream of air to a condensation zone formed by at least one generallyspirally disposed horizontal conduit having its lower portion open andimmersed in a body of cooling water and its upper surface cooled by awater spray, whereby said mercury vapor is condensed to liquid mercurywhich sinks to the bottom of said body of water; and

d. recovering said liquid mercury.

2. The process of claim 1 in which tide of mercury.

3. The process of claim 1 in which said body of mercury ore ismaintained in a said heating zone in a removable tray.

4. The process of claim 1 in which ore is heated to a temperaturebetween about 400 C. and about 650 C.

5. The process of claim 1 in which the temperatures of said vapors isreduced by said cooling water to about 20 C.

6. Apparatus for the recovery of mercury from mercury ores comprising,in combination:

a. a calcination and sublimation furnace including a hearth forcombustion of fuel to provide a heat source;

b. a heating and sublimation chamber located within said furnace andabove said hearth, said chamber being sealed against contact withcombustion gases from said hearth;

. means for injecting outside air into and in communication with theupper interior portion of said chamber;

d. a conduit connecting said chamber to an external vapor condensingsystem for transfer of mercury and other vapors from said heatingchamber to said condensing system; I

e. a vapor condensing system comprising at least one generally spirallydisposed horizontal conduit having its lower portion open and incommunication with a body of water, said conduit having its outer endconnected to said transfer conduit (d), and a trough positioned beneathsaid lower portion of said spiral conduit to receive condensed mercury,and means for supplying water to said trough.

7. The apparatus of claim 6 in which said spiral conduit comprises aninverted hollow half-round or half-tubular configuration forming itsupper portion, and includes means for spraying cooling water upon saidupper portion.

8. The apparatus of claim 6 in which said trough of the condensingsystem is provided with a sloping bottom to facilitate collection ofmercury, and means for removal of liquid mercury at the lower portion ofsaid sloping bottom.

said mercury ore is a sul-

2. The process of claim 1 in which said mercury ore is a sulfide ofmercury.
 3. The process of claim 1 in which said body of mercury ore ismaintained in a said heating zone in a removable tray.
 4. The process ofclaim 1 in which ore is heated to a temperature between about 400* C.and about 650* C.
 5. The process of claim 1 in which the temperatures ofsaid vapors is reduced by said cooling water to about 20* C. 6.Apparatus for the recovery of mercury from mercury ores comprising, incombination: a. a calcination and sublimation furnace including a hearthfor combustion of fuel to provide a heat source; b. a heating andSublimation chamber located within said furnace and above said hearth,said chamber being sealed against contact with combustion gases fromsaid hearth; c. means for injecting outside air into and incommunication with the upper interior portion of said chamber; d. aconduit connecting said chamber to an external vapor condensing systemfor transfer of mercury and other vapors from said heating chamber tosaid condensing system; e. a vapor condensing system comprising at leastone generally spirally disposed horizontal conduit having its lowerportion open and in communication with a body of water, said conduithaving its outer end connected to said transfer conduit (d), and atrough positioned beneath said lower portion of said spiral conduit toreceive condensed mercury, and means for supplying water to said trough.7. The apparatus of claim 6 in which said spiral conduit comprises aninverted hollow half-round or half-tubular configuration forming itsupper portion, and includes means for spraying cooling water upon saidupper portion.
 8. The apparatus of claim 6 in which said trough of thecondensing system is provided with a sloping bottom to facilitatecollection of mercury, and means for removal of liquid mercury at thelower portion of said sloping bottom.